Study the in vivo and in vitro biosynthesis pathway of the selenium prosthetic group of glutathione peroxidase. Study the kinetics involved in activation of selenium-glutathione peroxidase by various peroxide and sulfhydryl substrates. Study the potential antagonists of glutathione peroxidase that are of environmental concern, e.g., the metals mercury and cadmium. Study the molecular mechanisms of the selenium-containing molecule at the active site in glutathione peroxidase.